/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2006, 2009 INRIA
 * Copyright (c) 2009 MIRKO BANCHI
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
 * Author: Mirko Banchi <mk.banchi@gmail.com>
 */
#include "ap-wifi-mac-ctrl.h"

#include "ns3/assert.h"
#include "ns3/log.h"
#include "ns3/simulator.h"
#include "ns3/string.h"
#include "ns3/pointer.h"
#include "ns3/boolean.h"

#include "qos-tag.h"
#include "wifi-phy.h"
#include "dcf-manager.h"
#include "mac-rx-middle.h"
#include "mac-tx-middle.h"
#include "mgt-headers.h"
#include "mac-low.h"
#include "amsdu-subframe-header.h"
#include "msdu-aggregator.h"

NS_LOG_COMPONENT_DEFINE("ApWifiMacCtrl");

namespace ns3
{

NS_OBJECT_ENSURE_REGISTERED(ApWifiMacCtrl);

TypeId ApWifiMacCtrl::GetTypeId(void)
{
	static TypeId tid =
			TypeId("ns3::ApWifiMacCtrl").SetParent<RegularCtrlWifiMac>().AddConstructor<
					ApWifiMacCtrl>().AddAttribute("BeaconInterval",
					"Delay between two beacons",
					TimeValue(MicroSeconds(102400)),
					MakeTimeAccessor(&ApWifiMacCtrl::GetBeaconInterval,
							&ApWifiMacCtrl::SetBeaconInterval),
					MakeTimeChecker()).AddAttribute("BeaconGeneration",
					"Whether or not beacons are generated.", BooleanValue(true),
					MakeBooleanAccessor(&ApWifiMacCtrl::SetBeaconGeneration,
							&ApWifiMacCtrl::GetBeaconGeneration),
					MakeBooleanChecker());
	return tid;
}

ApWifiMacCtrl::ApWifiMacCtrl()
{
	NS_LOG_FUNCTION (this);
	m_beaconDca = CreateObject<DcaTxop>();
	m_beaconDca->SetAifsn(1);
	m_beaconDca->SetMinCw(0);
	m_beaconDca->SetMaxCw(0);
	m_beaconDca->SetLow(m_low);
	m_beaconDca->SetManager(m_dcfManager);

	// Let the lower layers know that we are acting as an AP.
	SetTypeOfStation(AP);

	m_enableBeaconGeneration = false;
}

ApWifiMacCtrl::~ApWifiMacCtrl()
{
	NS_LOG_FUNCTION (this);
}

void ApWifiMacCtrl::DoDispose()
{
	NS_LOG_FUNCTION (this);
	m_beaconDca = 0;
	m_enableBeaconGeneration = false;
	m_beaconEvent.Cancel();
	RegularCtrlWifiMac::DoDispose();
}

void ApWifiMacCtrl::SetAddress(Mac48Address address)
{
	// As an AP, our MAC address is also the BSSID. Hence we are
	// overriding this function and setting both in our parent class.
	RegularCtrlWifiMac::SetAddress(address);
	RegularCtrlWifiMac::SetBssid(address);
}

void ApWifiMacCtrl::SetBeaconGeneration(bool enable)
{
	NS_LOG_FUNCTION (this << enable);
	if (!enable)
	{
		m_beaconEvent.Cancel();
	}
	else if (enable && !m_enableBeaconGeneration)
	{
		m_beaconEvent = Simulator::ScheduleNow(&ApWifiMacCtrl::SendOneBeacon,
				this);
	}
	m_enableBeaconGeneration = enable;
}

bool ApWifiMacCtrl::GetBeaconGeneration(void) const
{
	return m_enableBeaconGeneration;
}

Time ApWifiMacCtrl::GetBeaconInterval(void) const
{
	return m_beaconInterval;
}

void ApWifiMacCtrl::SetWifiRemoteStationManager(
		Ptr<WifiRemoteStationManager> stationManager)
{
	NS_LOG_FUNCTION (this << stationManager);
	m_beaconDca->SetWifiRemoteStationManager(stationManager);
	RegularCtrlWifiMac::SetWifiRemoteStationManager(stationManager);
}

void ApWifiMacCtrl::SetLinkUpCallback(Callback<void> linkUp)
{
	NS_LOG_FUNCTION (this);
	RegularCtrlWifiMac::SetLinkUpCallback(linkUp);

	// The approach taken here is that, from the point of view of an AP,
	// the link is always up, so we immediately invoke the callback if
	// one is set
	linkUp();
}

void ApWifiMacCtrl::SetBeaconInterval(Time interval)
{
	NS_LOG_FUNCTION (this << interval);
	if ((interval.GetMicroSeconds() % 1024) != 0)
	{
		NS_LOG_WARN ("beacon interval should be multiple of 1024us, see IEEE Std. 802.11-2007, section 11.1.1.1");
	}
	m_beaconInterval = interval;
}

void ApWifiMacCtrl::StartBeaconing(void)
{
	NS_LOG_FUNCTION (this);
	SendOneBeacon();
}

void ApWifiMacCtrl::ForwardDown(Ptr<const Packet> packet, Mac48Address from,
		Mac48Address to)
{
	// If we are not a QoS AP then we definitely want to use AC_BE to
	// transmit the packet. A TID of zero will map to AC_BE (through \c
	// QosUtilsMapTidToAc()), so we use that as our default here.
	uint8_t tid = 0;

	// If we are a QoS AP then we attempt to get a TID for this packet
	if (m_qosSupported)
	{
		tid = QosUtilsGetTidForPacket(packet);
		// Any value greater than 7 is invalid and likely indicates that
		// the packet had no QoS tag, so we revert to zero, which'll
		// mean that AC_BE is used.
		if (tid >= 7)
		{
			tid = 0;
		}
	}

	ForwardDown(packet, from, to, tid);
}

void ApWifiMacCtrl::ForwardDown(Ptr<const Packet> packet, Mac48Address from,
		Mac48Address to, uint8_t tid)
{
	NS_LOG_FUNCTION (this << packet << from << to);
	WifiMacHeader hdr;

	// For now, an AP that supports QoS does not support non-QoS
	// associations, and vice versa. In future the AP model should
	// support simultaneously associated QoS and non-QoS STAs, at which
	// point there will need to be per-association QoS state maintained
	// by the association state machine, and consulted here.
	if (m_qosSupported)
	{
		hdr.SetType(WIFI_MAC_QOSDATA);
		hdr.SetQosAckPolicy(WifiMacHeader::NORMAL_ACK);
		hdr.SetQosNoEosp();
		hdr.SetQosNoAmsdu();
		// Transmission of multiple frames in the same TXOP is not
		// supported for now
		hdr.SetQosTxopLimit(0);
		// Fill in the QoS control field in the MAC header
		hdr.SetQosTid(tid);
	}
	else
	{
		hdr.SetTypeData();
	}

	hdr.SetAddr1(to);
	hdr.SetAddr2(GetAddress());
	hdr.SetAddr3(from);
	hdr.SetDsFrom();
	hdr.SetDsNotTo();

	if (m_qosSupported)
	{
		// Sanity check that the TID is valid
		NS_ASSERT(tid < 8);
		m_edca[QosUtilsMapTidToAc(tid)]->Queue(packet, hdr);
	}
	else
	{
		m_dca->Queue(packet, hdr);
	}
}

void ApWifiMacCtrl::Enqueue(Ptr<const Packet> packet, Mac48Address to,
		Mac48Address from)
{
	NS_LOG_FUNCTION (this << packet << to << from);
	if (to.IsBroadcast() || m_stationManager->IsAssociated(to))
	{
		ForwardDown(packet, from, to);
	}
}

void ApWifiMacCtrl::Enqueue(Ptr<const Packet> packet, Mac48Address to)
{
	// We're sending this packet with a from address that is our own. We
	// get that address from the lower MAC and make use of the
	// from-spoofing Enqueue() method to avoid duplicated code.
	Enqueue(packet, to, m_low->GetAddress());
}

bool ApWifiMacCtrl::SupportsSendFrom(void) const
{
	return true;
}

SupportedRates ApWifiMacCtrl::GetSupportedRates(void) const
{
	// send the set of supported rates and make sure that we indicate
	// the Basic Rate set in this set of supported rates.
	SupportedRates rates;
	for (uint32_t i = 0; i < m_phy->GetNModes(); i++)
	{
		WifiMode mode = m_phy->GetMode(i);
		rates.AddSupportedRate(mode.GetDataRate());
	}
	// set the basic rates
	for (uint32_t j = 0; j < m_stationManager->GetNBasicModes(); j++)
	{
		WifiMode mode = m_stationManager->GetBasicMode(j);
		rates.SetBasicRate(mode.GetDataRate());
	}
	return rates;
}

void ApWifiMacCtrl::SendProbeResp(Mac48Address to)
{
	NS_LOG_FUNCTION (this << to);
	WifiMacHeader hdr;
	hdr.SetProbeResp();
	hdr.SetAddr1(to);
	hdr.SetAddr2(GetAddress());
	hdr.SetAddr3(GetAddress());
	hdr.SetDsNotFrom();
	hdr.SetDsNotTo();
	Ptr<Packet> packet = Create<Packet>();
	MgtProbeResponseHeader probe;
	probe.SetSsid(GetSsid());
	probe.SetSupportedRates(GetSupportedRates());
	probe.SetBeaconIntervalUs(m_beaconInterval.GetMicroSeconds());
	packet->AddHeader(probe);

	// The standard is not clear on the correct queue for management
	// frames if we are a QoS AP. The approach taken here is to always
	// use the DCF for these regardless of whether we have a QoS
	// association or not.
	m_dca->Queue(packet, hdr);
}

void ApWifiMacCtrl::SendAssocResp(Mac48Address to, bool success)
{
	NS_LOG_FUNCTION (this << to << success);
	WifiMacHeader hdr;
	hdr.SetAssocResp();
	hdr.SetAddr1(to);
	hdr.SetAddr2(GetAddress());
	hdr.SetAddr3(GetAddress());
	hdr.SetDsNotFrom();
	hdr.SetDsNotTo();
	Ptr<Packet> packet = Create<Packet>();
	MgtAssocResponseHeader assoc;
	StatusCode code;
	if (success)
	{
		code.SetSuccess();
	}
	else
	{
		code.SetFailure();
	}
	assoc.SetSupportedRates(GetSupportedRates());
	assoc.SetStatusCode(code);
	packet->AddHeader(assoc);

	// The standard is not clear on the correct queue for management
	// frames if we are a QoS AP. The approach taken here is to always
	// use the DCF for these regardless of whether we have a QoS
	// association or not.
	m_dca->Queue(packet, hdr);
}

void ApWifiMacCtrl::SendOneBeacon(void)
{
	NS_LOG_FUNCTION (this);
	WifiMacHeader hdr;
	hdr.SetBeacon();
	hdr.SetAddr1(Mac48Address::GetBroadcast());
	hdr.SetAddr2(GetAddress());
	hdr.SetAddr3(GetAddress());
	hdr.SetDsNotFrom();
	hdr.SetDsNotTo();
	Ptr<Packet> packet = Create<Packet>();
	MgtBeaconHeader beacon;
	beacon.SetSsid(GetSsid());
	beacon.SetSupportedRates(GetSupportedRates());
	beacon.SetBeaconIntervalUs(m_beaconInterval.GetMicroSeconds());

	packet->AddHeader(beacon);

	// The beacon has it's own special queue, so we load it in there
	m_beaconDca->Queue(packet, hdr);
	m_beaconEvent = Simulator::Schedule(m_beaconInterval,
			&ApWifiMacCtrl::SendOneBeacon, this);
}

void ApWifiMacCtrl::TxOk(const WifiMacHeader &hdr)
{
	NS_LOG_FUNCTION (this);
	RegularCtrlWifiMac::TxOk(hdr);

	if (hdr.IsAssocResp() && m_stationManager->IsWaitAssocTxOk(hdr.GetAddr1()))
	{
		NS_LOG_DEBUG ("associated with sta=" << hdr.GetAddr1 ());
		m_stationManager->RecordGotAssocTxOk(hdr.GetAddr1());
	}
}

void ApWifiMacCtrl::TxFailed(const WifiMacHeader &hdr)
{
	NS_LOG_FUNCTION (this);
	RegularCtrlWifiMac::TxFailed(hdr);

	if (hdr.IsAssocResp() && m_stationManager->IsWaitAssocTxOk(hdr.GetAddr1()))
	{
		NS_LOG_DEBUG ("assoc failed with sta=" << hdr.GetAddr1 ());
		m_stationManager->RecordGotAssocTxFailed(hdr.GetAddr1());
	}
}

void ApWifiMacCtrl::Receive(Ptr<Packet> packet, const WifiMacHeader *hdr)
{
	NS_LOG_FUNCTION (this << packet << hdr);

	Mac48Address from = hdr->GetAddr2();

	if (hdr->IsData())
	{
		// special process
		WifiMacHeader myHdr;
		packet->PeekHeader(myHdr);
		if (myHdr.IsRts() || myHdr.IsCts()) //Rts for data channel
		{
			m_dca->NotifyDataChannel(packet, *hdr);
			return; // do NOT go to the normal process
		}

		Mac48Address bssid = hdr->GetAddr1();
		if (!hdr->IsFromDs() && hdr->IsToDs() && bssid == GetAddress()
				&& m_stationManager->IsAssociated(from))
		{
			Mac48Address to = hdr->GetAddr3();
			if (to == GetAddress())
			{
				NS_LOG_DEBUG ("frame for me from=" << from);
				if (hdr->IsQosData())
				{
					if (hdr->IsQosAmsdu())
					{
						NS_LOG_DEBUG ("Received A-MSDU from=" << from << ", size=" << packet->GetSize ());
						DeaggregateAmsduAndForward(packet, hdr);
						packet = 0;
					}
					else
					{
						ForwardUp(packet, from, bssid);
					}
				}
				else
				{
					ForwardUp(packet, from, bssid);
				}
			}
			else if (to.IsGroup() || m_stationManager->IsAssociated(to))
			{
				NS_LOG_DEBUG ("forwarding frame from=" << from << ", to=" << to);
				Ptr<Packet> copy = packet->Copy();

				// If the frame we are forwarding is of type QoS Data,
				// then we need to preserve the UP in the QoS control
				// header...
				if (hdr->IsQosData())
				{
					ForwardDown(packet, from, to, hdr->GetQosTid());
				}
				else
				{
					ForwardDown(packet, from, to);
				}
				ForwardUp(copy, from, to);
			}
			else
			{
				ForwardUp(packet, from, to);
			}
		}
		else if (hdr->IsFromDs() && hdr->IsToDs())
		{
			// this is an AP-to-AP frame
			// we ignore for now.
			NotifyRxDrop(packet);
		}
		else
		{
			// we can ignore these frames since
			// they are not targeted at the AP
			NotifyRxDrop(packet);
		}
		return;
	}
	else if (hdr->IsMgt())
	{
		if (hdr->IsProbeReq())
		{
			NS_ASSERT(hdr->GetAddr1 ().IsBroadcast ());
			SendProbeResp(from);
			return;
		}
		else if (hdr->GetAddr1() == GetAddress())
		{
			if (hdr->IsAssocReq())
			{
				// first, verify that the the station's supported
				// rate set is compatible with our Basic Rate set
				MgtAssocRequestHeader assocReq;
				packet->RemoveHeader(assocReq);
				SupportedRates rates = assocReq.GetSupportedRates();
				bool problem = false;
				for (uint32_t i = 0; i < m_stationManager->GetNBasicModes();
						i++)
				{
					WifiMode mode = m_stationManager->GetBasicMode(i);
					if (!rates.IsSupportedRate(mode.GetDataRate()))
					{
						problem = true;
						break;
					}
				}
				if (problem)
				{
					// one of the Basic Rate set mode is not
					// supported by the station. So, we return an assoc
					// response with an error status.
					SendAssocResp(hdr->GetAddr2(), false);
				}
				else
				{
					// station supports all rates in Basic Rate Set.
					// record all its supported modes in its associated WifiRemoteStation
					for (uint32_t j = 0; j < m_phy->GetNModes(); j++)
					{
						WifiMode mode = m_phy->GetMode(j);
						if (rates.IsSupportedRate(mode.GetDataRate()))
						{
							m_stationManager->AddSupportedMode(from, mode);
						}
					}
					m_stationManager->RecordWaitAssocTxOk(from);
					// send assoc response with success status.
					SendAssocResp(hdr->GetAddr2(), true);
				}
				return;
			}
			else if (hdr->IsDisassociation())
			{
				m_stationManager->RecordDisassociated(from);
				return;
			}
		}
	}

	// Invoke the receive handler of our parent class to deal with any
	// other frames. Specifically, this will handle Block Ack-related
	// Management Action frames.
	RegularCtrlWifiMac::Receive(packet, hdr);
}

void ApWifiMacCtrl::DeaggregateAmsduAndForward(Ptr<Packet> aggregatedPacket,
		const WifiMacHeader *hdr)
{
	MsduAggregator::DeaggregatedMsdus packets = MsduAggregator::Deaggregate(
			aggregatedPacket);

	for (MsduAggregator::DeaggregatedMsdusCI i = packets.begin();
			i != packets.end(); ++i)
	{
		if ((*i).second.GetDestinationAddr() == GetAddress())
		{
			ForwardUp((*i).first, (*i).second.GetSourceAddr(),
					(*i).second.GetDestinationAddr());
		}
		else
		{
			Mac48Address from = (*i).second.GetSourceAddr();
			Mac48Address to = (*i).second.GetDestinationAddr();
			NS_LOG_DEBUG ("forwarding QoS frame from=" << from << ", to=" << to);
			ForwardDown((*i).first, from, to, hdr->GetQosTid());
		}
	}
}

void ApWifiMacCtrl::DoStart(void)
{
	m_beaconDca->Start();
	m_beaconEvent.Cancel();
	if (m_enableBeaconGeneration)
	{
		m_beaconEvent = Simulator::ScheduleNow(&ApWifiMacCtrl::SendOneBeacon,
				this);
	}
	RegularCtrlWifiMac::DoStart();
}

} // namespace ns3
